[geeks] Has anyone used power-line communications?

[Bob]

>No, the problem is that DSL uses telephone lines to carry HF signals.
>Pretty much the same way that BPL does, e.g. multiple carriers at
different
>speeds. In fact, it would be accurate to look at BPL as DSL over power
lines
>instead of telephone lines.

AFAIK, DSL goes to 100 kHZ and ADSL goes to 1.1 MHz.  BPL goes up
to 80 MHz.  That's a tad different.  True, you can get harmonics from
DSL but BPL is right on SW frequencies. And with the repeaters on there
since it can't get past the "pole pigs" there is a lot of potential for
trouble.

>FIOS has eliminated that, but many places don't have FIOS. I have fiber
to
>a common point about 100 meters from my home, and then unshielded
telephone
>wire to my router.

>In some ways it's a moot point, someone at a telco is going to figure
out how
>to get the taxpayers to fund a bond issue for "infrastructure" and rip
out
>all of the copper wire so they can sell it a high price and replace it
with
>fiber which is made from plastic covered sand. :-)

Another advantage to fiber is it's a little hard to have an induced
voltage
appear on the line during a thunder storm or when the sun is really
pumping
out the solar wind during peak sunspot season.

>As for the ham causing DSL to crash, not likely. The devices use
adaptive
>technology and if a band is unsuable, switch to another one. That was
the
>big selling point of BPL, it could be programmed to avoid the narrow
bands
>that are allocated to hams, rendering their resistance moot. However no
one
>actually trusted a power company employee to not squeeze a little extra
>bandwidth by turning them on. :-(

They were on during the tests and when interference was found, they had
to "install" notch filters to reduce radiation in bands that were being
jammed.
Sometimes they didn't work well enough.

I was talking about BPL not DSL.  I was referring to a problem that was
called
"desensing" where the sensitivity of a receiving device is decreased by a
strong, nearby signal.  That used to be a problem for hams that would go
(before 9/11) to the top of WTC to see how far they can communicate due
to the height only to find out they couldn't hear anything because the
the
TV transmissions from the other tower.  I wouldn't be surprised if that
was
some of the communication problem during 9/11 between police, fire and
rescue communications, they might have been desensing each others'
radios.  I just wondered if that could happen to a BPL repeater.

Bob